52 CLINICAL FOCUS
52 CLINICAL FOCUS
4 AUGUST 2023 ausdoc . com . au
Therapy Update
Obstructive sleep apnoea in kids
Paediatrics
Dr Megan Sheppard ( left ) is an advanced paediatric trainee specialising in respiratory and sleep medicine . She has completed fellowships at both major paediatric tertiary centres in Sydney , NSW , most recently in the department of sleep medicine at the Children ’ s Hospital at Westmead , Sydney , NSW . Professor Karen Waters ( right ) is head of the departments of sleep medicine and long-term ventilation at the Children ’ s Hospital at Westmead , Sydney , NSW . She is a conjoint professor of child and adolescent health at the University of Sydney , NSW .
It is important to recognise , diagnose and treat this condition , to reduce adverse cardiological , neurological and behavioural effects .
NEED TO KNOW
Obstructive sleep apnoea ( OSA ) affects up to 5.7 % of children .
Early recognition and referral can prevent adverse neurocognitive , cardiovascular and behavioural effects .
Consider referring otherwise healthy children aged three and older , with snoring that is likely secondary to adenotonsillar hypertrophy , to an ENT surgeon .
High-risk groups can be identified .
Children with some syndromes and comorbidities require monitoring with regular polysomnography , irrespective of symptoms .
SNORING is the main symptom and sign of upper airway obstruction during sleep . Up to 14.8 % of children snore ‘ often ’ as reported by parents , and obstructive sleep apnoea affects 1.2-5.7 % of all children . 1 , 2
Obstructive sleep apnoea ( OSA ) is defined by the American Thoracic Society as a “ disorder of breathing during sleep characterised by prolonged partial or intermittent complete upper airway obstruction which impairs normal ventilation and sleep pattern ”. 3 However , in children the occurrence of repetitive apnoeas occurs at the severe end of the continuum of sleep disordered breathing . At the mild end , children can exhibit habitual snoring ( snoring ≥3 nights per week ) with no discrete apnoeas , gas exchange abnormalities or sleep fragmentation . It is important to diagnose and treat OSA as it is associated with adverse cardiological , neurological and behavioural effects . 4 This article will review the pathophysiology , aetiology , risk factors and associated adverse outcomes of OSA in paediatrics and offer practical guidelines for managing these patients in the Australian primary care setting .
Aetiology
Snoring represents turbulent airflow and indicates partial airway obstruction . The upper airway collapses with the onset of sleep due to the loss of muscle tone during sleep compared to wakefulness . Additional anatomical narrowing of the airway can then lead to partial or complete airway closure . The greatest risk of apnoea is
during REM sleep when muscle tone is lowest . Apnoeas during non-REM sleep are a marker of severe OSA apnoea in children . 5
Factors that can further increase airway collapsibility include neurological and muscular diseases causing low muscle tone or abnormal neuromotor reflexes . Anatomical airway narrowing in children is primarily caused by adenotonsillar hypertrophy which peaks during preschool years and is the major cause of OSA in otherwise healthy children . Airway narrowing can also be secondary to increased inflammation ( mucosal swelling ), micrognathia , retrognathia and midface hypoplasia associated with craniofacial syndromes , macroglossia or lingual tonsil hypertrophy . 2
The severity of OSA is classified by the apnoea-hypopnoea index ( AHI ) — see table 1 . 6 However , modifiers to these raw AHI values include baseline oxygen saturation and CO 2 levels , oxygen nadir , the occurrence of CO 2 retention ( at sleep onset , or acutely with periods of obstruction ), and the arousal index .
Risk factors
In Australian children , smoke exposure and non-Caucasian ethnicity are important risk factors for moderate or severe OSA . Preterm birth is associated with an increased risk of OSA , similarly a positive family history increases risk fourfold . 7 Obesity ( BMI > 95th centile ) becomes more significant in older , school-age children . Some studies report a history of asthma , allergic rhinitis and socioeconomic status as risk factors , however this is not consistent among Australian children . 4 Specific syndromes warrant screening for OSA from infancy onwards , due to their high risk for associated OSA because of the associated neuromuscular and / or anatomical abnormalities . These include trisomy 21 , Prader-Willi syndrome , achondroplasia , craniofacial syndromes ( Pierre Robin sequence ), neuromuscular disorders and certain metabolic conditions ( mucopolysaccharidoses ). Practitioners should have
Preterm birth is associated with an increased risk of OSA , similarly a positive family history increases risk fourfold . a high degree of suspicion for OSA in these populations and refer all cases to a paediatric sleep physician , even in the absence of symptoms .
Specific syndromes associated with OSA
Trisomy 21 is a common genetic condition that affects one in 650-1000 live births worldwide . 8 OSA occurs in 50-75 % of children with trisomy 21 with the full spectrum of disease seen from infancy onwards . 9 , 10 Symptoms are underrecognised with only 32 % of physicians and
There are medical and surgical management options , depending on severity of OSA .
39 % of carers reporting symptoms in patients who were subsequently diagnosed with OSA . 8
A variety of craniofacial conditions are predisposed to OSA due to unique facial structures which reduce airway size . Features can include midface hypoplasia , micrognathia , cleft lip and palate , glossoptosis and choanal atresia . Between 40-68 % of children with syndromic craniosynostosis have OSA , however diagnosis can be difficult and screening tools used in otherwise healthy children ( such as the Paediatric Sleep Questionnaire ) might not be valid in this population . 8
Neuromuscular conditions including Duchenne muscular dystrophy , Becker muscular dystrophy , limb – girdle muscular dystrophy , congenital muscular dystrophies , myotonic dystrophy , and spinal muscular atrophy predispose to OSA and hypoventilation . 11 Paediatric polysomnography ( PSG ) is essential in all groups as patients may not present with classic respiratory events . Hypoventilation ( CO 2 > 50mmHg ≥25 % of total sleep time ) in REM sleep is seen early in the course of disease , however with disease progression this can also occur in non-REM sleep . Predisposing factors include pharyngeal hypotonia , bulbar dysfunction and diaphragmatic weakness . Annual PSG , under the supervision of a paediatric sleep physician , should be performed in all children with a neuromuscular condition to screen for sleep disordered breathing and determine the need for overnight respiratory support , primarily bilevel ventilation .
First published online on 8 July 2023
Assessment
During a primary healthcare visit a history of snoring should be routine for any paediatric assessment . The Paediatric Sleep